Armstrong heads into the 29 kilometer women's event as defending champion, having won gold in Beijing four years ago from Emma Pooley (Great Britain) and Karin Thurig (Switzerland). Hers was the first medal for the US cycling team in Beijing.

"It's very special, but there is also some pressure," Armstrong said of her role. "I feel the pressure. Normally, a day or two before the time trial, I start feeling stress. Knowing that I am coming back trying to defend, I know I have a target on my back."

The 38-year-old finished 35th in Sunday's road race after a tonne of work after teammates Shelley Olds punctured while in the winning break. Armstrong crashed at the bottom of Box Hill, injuring her left side where she broke her clavicle May 24 after crashing during the prologue time trial of the Exergy Tour in her hometown of Boise, Idaho. Surgeons repaired the break with one screw the following morning and returned to racing at the Cascade Cycling Classic in late July.

"I am recovering from the hard effort on Sunday. It was a hard race," she admitted. "Everyone is trying to take two days to recover. The men have three days between, the women have two. The men raced longer, but when you're at this level, there is no fitness to be gained now. It's all about resting and recovering for tomorrow.

"I think the hurt that I am going to suffer during the race is by far going to outweigh the hurt that is on my elbow. It's a little sensitive, but it will not affect me. Once I am down on my pads [on the aerobars], it feels like I have a bruise."

Armstrong admits that a "challenging course" lies ahead for the 24 starters in the women's event, with a lot of variables and for this reason, it's hard to narrow down the possibilities for the podium.

"There are a lot of people who are riding very well right now. You can never count out the reigning world time trial champion, Judith Arndt (Germany). Clara Hughes (Canada) has come back out of retirement, just like I have, because we love this Olympic moment. She's here to do one thing, and that's to medal. Ellen Van Dijk (Netherlands), who is going to put down a good show. Trixi Worrack (Germany) had a great ride last week. Amber Neben (USA) is always consistent in her time trials. There is a big group of us who could medal. And you never know what you're going to get out of (road cycling gold medallist Marianne) Vos (Netherlands) tomorrow."

Armstrong's teammate, Neben successfully appealled the USA Cycling's Selection Committee's decision to choose Armstrong over her for the individual time trial at the UCI Road Cycling Championships in Copenhagen last year. Armstrong had already travelled to Europe when the arbitrator made the ruling, and she found out about the decision just hours after landing in Denmark.

Neben says that while she knows that her teammate is "so motivated" the 37-year-old believed it's hard to go past the three women that have made up the last two world championship podiums - Arndt, Pooley and Linda Villumsen (New Zealand).

"I think those three are super dangerous," Neben stated. "Clara Hughes (Canada) coming back. Ellen van Dijk (Netherlands). I think the time gaps are going to be really close. You are going to have to have that perfect day."

Neben explained she is also a big fan of the course.

"I think it is a beautiful time trial course. It's a true time trial course. Long sections where you have to roll the power and the speed. A few different areas where you have to think about a pacing strategy."

The 2008 World Time Trial Champion is hopeful of posting a top result on Wednesday.

"I didn't come here not to medal," Neben said. "God has got me in his hands and I am going to ride with His strength tomorrow and see what's going to happen. I am certainly shooting for the podium if not the gold medal."

For the men, the form of Phinney was evident with his fourth placing in Saturday's road race and is considered among the top four contenders for the 2012 Olympic title.

"I got fourth place in the road race and was happy to be up there," he explained. "But it was one of the more difficult places to get at the Olympic Games, and leaving the race with nothing after being so close to a medal. So I know my form is good and I have really been working specifically for this. I know that if I have a really good ride I can be up there and I am hungry from the road race. That's extra motivation.

"I would love to get a medal tomorrow but I know it is a pretty big task with [Bradley] Wiggins (Great Britain), [Chris] Froome (Great Britain), Tony Martin (Germany), Fabian Cancellara (Switzerland). You know, older than me and more experienced. They've proved themselves in the past to be very, very good, obviously. But I am up-and-coming."

Wednesday's starters took a first-hand look at the 44km course and Phinney believes that it's one that plays to his strengths.

"You know it is a little bit tricky finding your way, finding the right way through some of the roads," he said. "They are a little bit bumpy, but we are used to that. I think it is going to be really cool, the last couple of kilometers coming through Bushy Park. There will be a ton of people going round that pond and finishing up. It is going to be really, really special. I think it's a great course."